Automotive air-pollution preventive system

ABSTRACT

An air-pollution preventive system to be used in combination with an automotive internal combustion engine having a carburetor of variable venturi type, which system comprises a deceleration passage to supply an air-fuel mixture to the engine in an amount and mixture ratio that are suited for the engine operation during deceleration, the deceleration passage being closed and opened by valve means which is controlled upon driving conditions of the motor vehicle particularly upon vehicle speeds, positions of the clutch pedal, vacuum in the intake manifold of the engine, or combinations of two or more of these variables.

United States Patent 1191 Toda et al. 1 5] July 2, 1974 AUTOMOTIVE AIR-POLLUTION 2,091,148 8/1937 Hughes et al. 200/153 M NT; 3,146,844 9/1964 Carlson .1 123/97 B PREVE E S YSTEM 3,444,848 5/1969 Lawrence.. 123/119 1 Inventors: Yoshlo Toda, Yokohama; M3531! 3,460,814 8/1969 ONeill....... 123/97 B Shiobara, Chigasaki; Mitsutaka 3,486,595 12/1969 Turner... 192/.092 Konno, Yokohama, all of Japan 3,547,089 12/1970 Pierlot 1 123/97 B 3,601,106 8/1971 N k 123/97 B [73] Asslgnee: Nissan Motor Company, Yokohama a ajlma City, Japan Primary Examiner-Benjamin W. Wyche [22] 1972 Attorney, Agent, or FirmRobert E. Burns; Emman- [21] Appl. No.: 228,127 uel J. Lobato; Bruce L. Adams Related US. Application Data [63] Continuation-impart of Ser. No. 7,850, Feb. 2, I970,

abandoned. [57] ABSTRACT An air-pollution preventive system to be used in com- [30] Foreign Application Pnonty Data bination with an automotive internal combustion en- Feb. 5, 1969 Japan 44-8255 g having a carburetor of variable venturi yp Feb. 5, 1969 Japan 44-8256 which System comprises a deceleration p g to p ply an air-fuel mixture to the engine in an amount and [52] 123/97 zoo/153 74/843 mixture ratio that are suited for the engine operation 192/062 during deceleration, the deceleration passage being [51 1111:. C1. F0211 closed and opened y Valve means which is controlled [58] held of Search 123/97 81 ZOO/153 upon driving conditions of the motor vehicle particu- ZOO/159 A larly upon vehicle speeds, positions of the clutch pedal, vacuum in the intake manifold of the engine, or [56] References C'ted combinations of two or more of these variables.

UNITED STATES PATENTS 748,409 12/1903 McLean 200/153 M 1 Claim, 8 Drawing Figures I V? D '11 s II-IIIIIS Ill/11110 PATENTEDJUL 2 i974 SHEEI 1 BF 4 K. m a

FIG. /A

- PAIENTEB JUL? I974 SHEU 0F 4 AUTOMOTIVE AIR-POLLUTION PREVENTIVE SYSTEM This is a continuation-in-part application of prior application Ser. No. 7,850 filed Feb. 2, 1970 and now abandoned.

This invention relates to a vehicular air-pollution preventive system for use with an automotive gasolinepowered internal combustion engine and, more particularly, to an air-pollution preventive system to be combined with an automotive internal combustion engine having a carburetor of variable venturi type, which system is adapted to reduce the concentration of the unburned content of the exhaust gases emitted from the engine during deceleration. The carburetor is constructed in such a manner that both the variable choke member and fuel-metering device are operated by a suction-operated piston or bellows and that the suction existing in the mixing chamber between the variable choke and the throttle valve is used to operate the piston or bellows.

During deceleration of the motor vehicle when the throttle valve of the carburetor is substantially closed, the flow of air-fuel mixture is practically shut off at the throttle valve to cause the vacuum in the intake manifold to rise abruptly. The amount of mixture ratio of the air-fuel mixture is usually determined to suit the idling operation of the engine. The engine is thus supplied during deceleration with an air-fuel mixture which is calibrated to enable the engine to operate satisfactorily during the idling, not the decelerating, operation. This is reflected by degraded combustion efficiency and misfiring in the combustion chamber of theengine during deceleration so that a certain amount of unburned content which is largely hydrocarbons is emitted from the engine to the open air.

To solve the vehicular air-pollution problems to be traced to such emission of unburned toxic content or engine exhaust gases, the air-pollution system proposed by this invention is constructed and arranged in such a manner that an air-fuel mixture of optimum amount and mixture ratio is fed during deceleration to the engine through a bypass mixture passage which communicates both with the mixing chamber and with the intake manifold. The additional bypass passage is herein referred to as deceleration bypass passage because it is operable only during deceleration.

The concentration of unburned hydrocarbons in the exhaust gases, as is well known, varies markedly with the amount of mixture ratio of an air-fuel'mixture to be fed to the engine during deceleration from either high speed or low speed driving. Experiments thus far conducted have revealed that the hydrocarbon content peaks up for the decelerating mode especially from high speed driving.

During deceleration from the high speed driving when the throttle valve of the carburetor is substantially closed with the engine still operating at a high speed, a decreased amount of air-fuel mixture is drawn to the combustion engine and, on top of this, the mixture drawn to the combustion chamber is leaned out with the exhaust gases, impairing the ignition efficiency. This is a major cause of the incomplete combustion and misfiring as experienced during deceleration. Thus, it will be advantageous for reducing throughout the varying driving conditions of the motor vehicle the concentration of unburned hydrocarbons in the exhaust gases to have the engine supplied with an increased amount of air-fuel mixture during deceleration especially from the high speed driving.

The concentration of hydrocarbons remaining unburned in the exhaust gases will also be reduced throughout the varying driving conditions of the motor vehicle if the engine is supplied with air-fuel mixture of optimum mixture ratio during deceleration from the high speed driving.

With these in mind, the invention proposes to provide a bypass mixture passage in the carburetor of variable venturi type, which passage is operable only for the decelerating mode, whereby an additional airfuel mixture of optimum amount and mixtureratio is supplied to the engine during deceleration from the high speed running.

This bypass passage is, according to the invention, opened and closed by a solenoid valve assembly which, in turn, is controlled by control means by detecting the high speed conditions of the motor vehicle. Here the deceleration passage is adapted to remain opened while the motor vehicle is running at a speed exceeding a predetermined level. Since practically no pressure difference does exist between the mixing chamber and the intake manifold for such high speed or cruising conditions, however, the air-fuel mixture in the mixing chamber is passed directly into the intake manifold, not via the bypass passage. During deceleration from the high speed driving with the throttle valve substantially closed, apredetermined amount of air-fuel mixture is delivered from the mixing chamber through the deceleration passage into the intake manifold due to the abruptly increased pressure difference. In this instance, the mixture ratio can be determined to be optimum by the cooperation of the effective venturi area and fuelmetering device. Although the throttle valve is substantially fully closed during idle or deceleration from the low speed running, an air-fuel mixture passing through the effective throttle area can maintain satisfactory combustion in the engine. This is because the vacuum in the intake manifold is limited under such a level as to require to have the deceleration passage opened. It is' to be noted here that the air-pollution preventive system according to the invention is adapted to reduce the hydrocarbons contained in the engine exhaust gases throughout all running conditions of the motor vehicle without detriment to the engine performance.

It is thus an object of the invention to provide a vehicular air-pollution preventive system for use with an automotive internal combustion engine having a carburetor of variable venturi type to reduce the concentration of unburned content of the engine exhaust gases emitted during deceleration.

It is another object of the invention to provide an airpollution preventive system to be combined with an automotive internal combustion engine having a variable venturi carburetor to supply the engine with an air-fuel mixture of an amount and mixture ratio that are specifically suited for the deceleration from the high speed driving through the bypass deceleration passage.

In order to achieve these objects, the air-pollution preventive system according to the invention is controlled on the vehicle speeds, engine speeds or intake manifold vacuums. Where the vehicle speed, in particular, is to be utilized, the speed may be directly detected by a suitable speed detector and, if preferred, the same may be represented by a selected gear ratio or, more specifically, by the position of the speed selector lever if the control means is used together with a manually controlled transmission system or by the hydraulic pressued applied to the front and rear clutches if the control means is used with an automatic transmission system. Where the engine speed is to be utilized, it may be directly detected by a suitable engine revolution detector.

In the drawings:

FIG. 1 is a schematic view of an overall construction of an embodiment of the air-pollution preventive system according to the invention in which the control means is used together with a manually controlled transmission system and is operative responsive to changes in the vehicle speed and the position of a clutch pedal;

FIG. 1A is a schematic sectional view of the carburetor shown in FIG. 1;

FIG. 2 is a partially sectional view showing, on an enlarged scale, a preferred arrangement of transmission switch means for use in the control means of FIG. 1;

FIG. 3 is a partially sectional view showing, on an enlarged scale, a preferred arrangement of clutch switch means used in the control means of FIG. 1;

FIG. 4 is a sectional view showing the detailed contruction of a switch element of the transmission switch means of FIG. 2, which switch element is also applicable to the clutch switch means of FIG. 3;

FIG. 5 is similar to FIG. 1 but shows a modification of the system, in which the control means is used together with an automatically controlled transmission system and is operative responsive to changes in the vehicle speed;

FIG. 6 is a sectional view showing the detailed construction of a front or rear clutch piston switch means of FIG. 5; and

FIG. 7 is also similar to FIG. 1 but shows another modification of the system, in which the control means is operative responsive directly to the vehicle speed.

Through the accompanying drawings, the airpollution preventive systems of the invention, which are generally denoted by numerals 10, 10 and 10" in FIGS. 1, 5 and 7, respectively, are used as customary in combination with a conventional carburetor 11,of variable venturi type. The carburetor 11 of this type has an in intake passage 20 and a throttle valve 13 which controls the effective area of the intake passage 20 and which is shown as substantially closed to effect the deceleration of the motor vehicle. The carburetor has a variable choke member 31 cooperating with a bridge or constricted wall (not numbered) formed in the intake passage 20. The intake passage 20 below the choke member 31 is constructed by the bridge and the choke member 31 and has formed therebetween a choke 12a of variable area the effective cross-sectional area of which is varied or controlled by changes in the position of the choke member 31. A fuel jet nozzle or orifice means 37 opens into the choke 12a to supply fuel thereto. A mixing chamber 12 is defined in the intake passage 20 downstream of the choke 12a and upstream of the throttle valve 13. Designated by 14 is an intake manifold of the engine and by 15 and 15' are a manually controlled transmission system with a clutch pedal 16 and an automatically controlled transmission system, respectively. The electrical connections of the control means are shown to include, as preferable, an

ignition switch 17, fuse 18 and battery 10 all connected in series.

According to the invention, a bypass deceleration passage 21 is led from the mixing chamber 12 and opened into the intake manifold 14 past a valve head 22 of a solenoid valve assembly 23. The solenoid valve assembly 23 is shown as fixedly mounted on a base member 24 acting as a valve seat for the valve head 22. The base member 24 is, in turn, mounted on a connecting member 25 which may be fast on the wall of the intake manifold 14, if desired. The connecting member 25 may internally communicate with another connecting member (not shown) through a conduit 26, where a carburetor of dual or twin type having a pair of similar carburetors is used. If a single carburetor is used, however, the solenoid valve assembly 23 may be directly mounted on the wall of the intake manifold 14.

The carburetor is connected tightly with the intake manifold 14 by means of a suitable seal member 27. The deceleration passage 21 is at one end opened at a deceleration port 28 and communicates with the intake manifold 14 through the base member 24 and connecting member 25 at the other end 29 which is securedly and air-tightly connected to the base member 24.

In FIG. 1, the carburetor 1 1 is shown to be of conventional variable venturi type having the variable choke member 31. The choke member 31 is integral with a suction-operated piston 32 slidably mounted in a housing 35 fixed to the wall 6 of the carburetor 11. A piston rod 33 is secured to the choke member 31 and guides the movement of the piston 32 and the choke member 31. The piston rod 33 has provided therein an oil damper (not shown) for assuring the stability of the movement of the piston and the choke member. The piston 32 and the choke member 31 have each formed centrally in their interiors a hollow. These hollows and the space in the housing 35 above the piston 32 form a variable volume suction chamber 11a. The space in the housing below the piston 32 forms a variable atmospheric chamber 32b communicating with atmospheric pressure Po through a passage 5 formed in the carburetor wall 6. A compression spring 34 is provided in the suction chamber 11a for biasing the piston 32 and the choke member 31 downwardly (as viewed in the drawing). A jet needle 36 is mounted on the bottom of the choke member 31 and cooperates with the fuel jet nozzle 37 formed in the bridge and open into the venturi 12a. The jet needle 36 controls or meters the flow of fuel passing through the jet nozzle 37 into the venturi 12a by controlling the effective area of the jet nozzle 37 in accordance with the movement of the choke member 31 so as to increase the effective area of the jet nozzle 37 as the area of the choke 12a is increased. Fuel is supplied from a float bowl or chamber (not shown) into a fuel reservoir 38 below the jet nozzle 37. A suction (pressure P) is produced in the venturi 12a due to the flow of air passing through the venturi during moved or operated up and down due to changes in the suction and is held in a position in which the upward force is balanced by the downward force. The suction is varied in accordance with changes in the amount of flow of air passing through the venturi 12a and consequently the speed of flow of the air. When the throttle valve 13 is opened wider, the speed of the air passing through the venturi 12a increases the suction (decreases pressure P). As a result, the piston 32 is moved upwardly to increase the cross-sectional area of the venturi 12a so that the speed of the air passing through the venturi 12a decreases to reduce the suction (increase the pressure P). As a result the piston 32 moves downwardly and once again becomes balanced.

The deceleration passage 21 is supplied with an airfuel mixture formed of air supplied to the mixing chamber 12 through the choke 12a and fuel supplied from the fuel jet nozzle 37 to the mixing chamber 12 through the choke 12a and is dimensioned to pass an air-fuel mixture having a predetermined volume and air-fuel ratio optimum for maintaining satisfactory combustion in the engine during deceleration.

The flow of air-fuel mixture through the deceleration passage 21 is controlled by the solenoid valve assembly 23 according to the invention. The solenoid valve assembly 23 has, as usual, the valve head 22 which extends movably into the deceleration passage 21. The valve head 22 is usually held in a protruded position to close the deceleration passage 21 which position is projected from the retracted position to open the deceleration passage 21 which position is shown in FIG. 1 by the action of suitable means such as a compression spring 8 to. The solenoid valve assembly 23 also has a solenoid coil 30 which is a first control means and a core 40 integral with the valve head 22 and surrounded by the solenoid coil 30. The solenoid coil 30, when excited, forces the core 40 from the protruded position to the retracted position in a direction in which the valve head 22 retracts from the deceleration passage 21 against the action of the compression spring, if any. The solenoid coil 30 is electrically connected with control means of the construction to be described later and is excited only when the motor vehicle runs at a speed exceeding a predetermined level.

With the deceleration passage 21 and the solenoid valve assembly 23 thus constructed and arranged, the valve head 22 is normally held in the protruded position to close the deceleration passage 21 with the solenoid coil 30 kept unexcited, thereby shutting off the flow of air-fuel mixture through the decelerationpassage 21. When, however, the solenoid coil 23 becomes excited in response to the high vehicle'speed, then the valve head 22 is moved in the retracted position to open the deceleration passage 21, thus permitting the air-fuel mixture to be pulled over by the high vacuum into the intake manifold 14 through the deceleration port 28 and passage 21.

Under the operations of the motor vehicle excepting the deceleration from the high speed driving, however, the air-fuel mixture passes mainly through the effective area of the intake passage which is determined by the opening of the throttle valve 13. More specifically, the mixture is drawn through the passage 21 into the intake manifold 14 only when a remarkable pressure difference occurs between the mixing chamber 12 and intake manifold 14. Thus, the deceleration passage 21 can be left open while the vehicle or engine speeds are in excess of a predetermined level. As a result, the solenoid valve assembly 23 can be controlled with use of the control means of relatively simple construction and arrangement in the air-pollution preventive system according to this invention.

The control means to excite and de-energize the solenoid coil of the solenoid valve assembly 23 may be constructed and arranged in different ways depending upon the control factors selected to govern the timings of the air-fuel mixture being delivered to the engine through the deceleration passage 21. Although a variety of control factors may be conceivable, the invention proposes to use, as preferable, any of vehicle speeds, engine speeds or intake manifold vacuums for the purpose of detecting the high speed condition of the motor vehicle.

Where the vehicle speed, in particular, is to be utilized, it may be preferable to have the control means constructed to be responsive to vehicle speeds within a predetermined range. If, in this instance, the airpollution preventive system according to the invention is to be used together with an automatic transmission system, the control means may be controlled either by the fluid pressure in the hydraulic circuits in the transmission system or by electrically detecting the vehicle speed ratios selected by the transmission system or engine speeds, which will be discussed in conjunction with FIG. 5. If, on the other hand, the transmission system is of the manually operated type, the vehicle speed will be indexed as the positions of ,the clutch pedal and of the fork rod in the power train.

The control means as used in the air-pollution preventive system 10 of FIG. 1 which is a second control means is constructed essentially as a speed detector switch means 41 operatively mounted on the manually controlled transmission system 15 having a shift lever 42, and clutch switch means 43 operatively mounted on the clutch pedal 16, of which constructions are to be described and shown later. The solenoid valve assembly 23 is electrically connected at one terminal by a line 44 with a power source or battery 19 preferably through the ignition switch 17 and fuse 18 and at the other by a line 45 with the switch means 43 which, in turn, is connected by a line 46 with one terminal of the speed detector switch means 41. The other terminal of the speed detector 'switch means 41 is grounded through a line 47. Thus, the solenoid valve assembly 23 and clutch switch means 43 are connected electrically in series.

It will be appreciated that the control means constituted by these vehicle speed detector switch means 41 and clutch switch means 43 is operable when and only when the two means connected in series are concurrently closed and that the solenoid valve assembly 23 is consequently actuated only when the vehicle speed is limited within a predetermined range. If at least either of the two means 41 and 43 remains opened, then the solenoid valve assembly 23 is kept at rest so that no air-fuel mixture is passed over to the engine through the deceleration passage 21. When the motor vehicle is in the idle operation with the transmission system held in its neutral condition, the speed detector switch means 41 is opened thereby keeping the solenoid valve assembly 23 deenergized. When the motor vehicle is in the idle operation with the clutch pedal 16 depressed by an operator, the switch means 43 is opened thereby keeping the solenoid valve assembly 23 deenergized.

normal cruising and accelerating operations with the throttle valve 13 partly or fully opened, the speed switch means 41 and the switch means 43 are both closed thereby keeping the solenoid valve assembly 23 energized'to open the deceleration passage 21. In such a condition, when the throttle valve 13 is substantially closed so that the motor vehicle is in the decelerating operation, an additional air-fuel mixture is drawn through the deceleration passage 21 into the intake manifold by the intake manifold vacuum.

The concentration of unburned hydrocarbons in the engine exhaust gases is higher during deceleration from high speeds than from low speeds, as has been discussed. Since higher gear ratios are usually selected during the high speed driving, it will be beneficial for the reduction of the concentration of unburned hydrocarbons to have the solenoid valve assembly 23 actuated especially in the deceleration from the high speed driving. It is desirable for this very reason that the detector 41 and switch means 43 be constructed in a manner to excite the solenoid valve assembly 23 only when the motor vehicle is running at higher speeds, for example, at the third or fourth driving speed ratio in a fourshift transmission system or at the third driving speed ratio in a three-shift transmission system. 1

Where a transmission system of the manually operated type is to be used with the air-pollution preventive system of FIG. 1 according to the invention, the detection of the speeds selected in the transmission system may be effected with use of the speed detector 41 and switch means 43 which are illustrated in FIGS. 2 and 3, respectively.

In FIG. 2, the speed detector 41 has a pair of lead terminals 48a and 48b and a moving member 49 made of an insulating material. The shift lever 42 is operatively connected to the transmission system 15 through supporting membersSl and 52. The transmission system 15, which is herein shown in its neutral position, has a striking rod 53, which is operatively connected to a fork rod 54 through a connecting member 55, as customary. The striking rod 53 is operatively connected through the supporting member 52 to the shift lever 42. The fork rod 54 is also connected securely to a shifting rod (not shown) to selectively couple and uncouple the transmission gears (not shown) as the striking rod 53 is moved back and forth by the shift lever 42.

The speed selected in the transmission system 15 having such elements is detected by the speed detector 41, if the transmission system is of four-shift type, and if two different recesses (not shown formed in the peripheral wall of the fork rod 54 at locations suited to detect the third and fourth driving speed ratios, respectively, selected. Where a three-shift transmission system is to be used, only one recess may suffice to detect the third driving speed ratio as indicated at 56 in FIG. 2.

The speed detector 41 is constructed in a manner to detect the movement of the fork rod 54 through mechanical engagement with the recess or recesses and to become operative when the recess or recesses seize the clutch pedal 16 is detected through mechanical engagement with the recess provided therein. The switch means 43 becomes operative only when the moving member 61 is captured by the recess. Thus, the construction and operation of the switch means 43 is essentially similar to those of the speed detector 41. A preferred form of these two elements 41 and 43 will be described in detail with reference to FIG. 4.

In FIG. 4, the switch element which is generally represented by numeral 41 or 43 has a moving member 49 or 61 made of an insulating material and projecting outwardly from its housing 62 toward a moving object (not shown) which is actually the striking rod 53 (FIG. 2) or clutch pedal 16 (FIGS. 1 and 3). The housing 62 may be, if desired, threaded at its end portion 63 for mounting the speed detector 41 and switch means 43 on the structure of the transmission system 15 and supporting plate 57, respectively. The moving member 49 or 61 is in a preferred form comprised by an insulator member 64, a conductor member 65 acting as a moving contact and a recessed insulator member 66, as shown. A compression spring 67 with fixed end is received in the recess of the insulator member 66 in a manner to force the moving contact 64'and moving member 49 or 61 toward the moving object ahead of them. The switch element also has a pair of stationary contacts 68a and 68b connected with lead terminals 48a or 59a and 48b or 59b, respectively. The stationary contacts 68a and 68b-are fixedly mounted on the housing 62 by means of-a pair of supporting members 69a and 69b, and 71a and 71b, respectively, made of insulating materials, as shown. The stationary contacts 68a and 68b are positioned in such a manner that they are usually in abutting engagementwith the insulator member 66 and the moving contact 65, respectively by the action of the compression spring 67. The lead terminals 48a or 59a and 48b or 59b are thus usually disconnected from each other so that the solenoid coil of the solenoid valve assembly 23 is kept unexcited. When, however, the moving object moves toward the leading tip of the moving member 49 or 61, then the moving contact 65 is moved against the action of the spring 67 in a direction opposite to the moving object. The result is that the moving contact 65 is brought into abutting engagement with the stationary contacts 68a and 68b to connect the lead terminals 48a or 59a and 48b or 59b, respectively, with each othenThe solenoid coil of the solenoid valve assembly 23 is thereby excited and an optimum air-fuel mixture is permitted to pass into the combustion chamber through the deceleration passage 21 (FIG. 1).

It will be understood that although an electrical contact is made when the moving member 49 or 61 is moved into the housing 62, alternatively a moving contact, comparable to moving contact 65 in FIG. 4 may be arranged so that an electrical contact is made when the moving member is moved out of the housing of the detector. This would depend on the nature of the element being detected.

The speed detector and switch means to achieve this purpose may be combined together to be operable in accordance with changes in the fluid pressures in the hydraulic control circuit of the automatic transmission system 15', as shown in FIG. 5. The fluid pressures occurring at the actuating elements of the brakes and clutches of the automatic transmission system are known to vary with the speed ranges. In order to detect the high speed driving conditions, therefore, the speed detector and switch means may be constructed in such a manner as to be responsive to changes in the fluid pressures carried to the front and rear clutch pistons.

For this purpose, the combinedspeed detector and switch means may be made up of two switch elements 72 and 73 connected in series with each other. The switch elements 72 and 73 are herein termed the front and rear clutch piston switches, respectively.

In FIG. 5, the front clutch piston switch 72 is connected with the solenoid valve assembly 23 and rear clutch piston switch 73 through the lines 74 and 75, respectively. The rear switch 73 is grounded via a line 76. The other operating members shown in FIG. are essentially similar to those of FIG. 1 so that discussion is limited to the construction and operation of the switches 72 and 73. In this instance, these switches 72 and 73 are constructed similarly to each other and, hence, only one of them is illustrated in FIG. 6.

Referring to FIG. 6, the front clutch piston switch 72 has its housing 77 threaded at an end portion 78 to be secured to the structural wall of the transmission system This front clutch piston switch element 72 has a chamber 79 with an air vent 81 and a chamber 82 which is separated from the former by a diaphragm member 83. The chamber 79 is an atmospheric chamber which is vented to the open air through the air vent 81 while the chamber 82 is a fluid chamber which communicates with the piston chamber of the front clutch piston (not shown). A moving member 84, which is made of an insulating material, is mounted on the diaph agm member 83 and extends into the atmospheric chamber 79. The moving member 84 is connected at its leading end with a moving contact 85 of a conductive material, as shown. The diaphragm member 83 is usually forced toward the fluid chamber 82 by the action of a compression spring 86. The switch element 72 has a pair of stationary contacts 87a and 87b connected with lead terminals 88a and 88b, respectively. The stationary contacts 87a and 87b are positioned in such a manner that they are usually in an abutting engagement with the moving member 84 when the diaphragm member 83 is forced toward the fluid chamber 82 overpowering the fluid pressure present in the fluid chamber 82. Thus, the lead terminals 88a and 88b are usually kept disconnected from each other to maintain the solenoid coil of the solenoid valve assembly 23 deenergized. When, however, an increased fluid pressure is carried into the fluid chamber 82, then the diaphragm member 83 is moved against the action of the compression spring 86 toward the atmospheric chamber 79 so that the moving contact 85 integral with the moving member 84 is brought into a position in which it is seized by the stationary contacts 87a and 87b. The lead terminals 88a and 88b are thus interconnected with each other and as the consequency the solenoid coil becomes excited.

The rear clutch piston switch elements 73, though constructed entirely similarly to the front clutch piston switch element 72, is arranged in a manner that the fluid pressure is drawn from the piston chamber of the rear clutch piston (not shown).

With the front and rear clutch piston switch elements 72 and 73, respectively, combined in series with each other, ON and OFF" signals representing the high and low fluid pressures, respectively, are made available.

It will be appreciated that the speed detector and switch means made up of the front and rear clutch piston switch elements 72 and 73 can be closed and the solenoid valve assembly 23 can be actuated only when the third driving speed, for example, is detected by the switch means. The concentration of the unburned hydrocarbons in the exhaust gases emitted from the engine during deceleration can be thus reduced significantly as already discussed with reference to FIG. 1.

The control means thus being constructed, the solenoid valve assembly 22 will be actuated also during acceleration and normal cruising. The throttle valve 14 of the carburetor 11 in this instance is partly open to permit the passage of air-fuel mixture therethrough and the vacuum in the intake manifold 14 is far lower than the vacuum built up during deceleration. The amount of air-fuel mixtureto be drawn to the engine through the deceleration passage 21 is practically negligible as compared with the amounts of air-fuel mixtures to be supplied through the main supply passage.

As an alternative to the speed detector and switch means, the control means may be constructed as a switch of the nature which is responsive to the vehicle speed detected electrically from the output shaft of the transmission system, an example being illustrated in FIG. 7.

In FIG. 7, the high speed conditions of the motor vehicle are detected by a speed sensor 89 of known type. The switch of such nature is generally indicated by numeral 91 which is shown to be combined with a transmission system 15 or 15. The transmission system 15 or 15' to which the switch 91 is to be applied may be either automatic or manually controlled type.

The switch 91 per se may be constructed and arranged in some suitable manners inasmuch as the intent of operating on predetermined vehicle speeds is maintained and the construction arrangement as shown and described is presented solely for illustrative purposes.

A speed meter cable 92 is operatively connected with the vehicle speed sensor 89. The switch 91 as shown has a vehicle speed detector 93 which is connected with and operated by the speed sensor 89 through the speed meter cable 92. The speed sensor 89 is, for example, so arranged as to constantly supply the speed detector 93 with a voltage corresponding to the vehicle speed selected in the transmission system 15 or 15'. The speed detector 93 having a solenoid 94 is connected to a relay switch 95. The relay switch 95 is constructed in a manner to remain open normally and to be closed once the voltage which the speed detector 93 receives from the speed sensor 89 of the transmission system exceeds a predetermined level, say about 20 km/hr. for example.

As shown, the speed detector 93 and sensor 89 are electrically connected with the power supply 19 by way of lines 96, 97 and 98. The speed sensor 89 and detector 93 are grounded at one terminal thereof via lines 99 The switch 91 thus constructed, the control means in this arrangement acts to keep the solenoid coil of the solenoid valve assembly 23 actuated when the vehicle is driven at a speed higher than the predetermined level, for instance, of 20 km/hr. Even if, therefore, the motor vehicle starts to slow down with the carburetor throttle valve 14 kept substantially closed, the engine can still receive through the deceleration passage 21 an air-fuel mixture of an amount and mixture ratio that are determined to best suit the deceleration of the motor vehicle, as previously discussed. In this example, too, an air-fuel ratio is invariably supplied to the engine through the deceleration passage 21 during acceleration and normal cruising of the motor vehicle. The amount of the air-fuel mixture to be passed through the deceleration passage 21 is practically negligible for the same reason as mentioned in connection with FIG. 1. In operations at a vehicle speed lower than the predetermined level (20 km/hr. for example) including the parking or standing, the relay switch 95 is held open so that the solenoid valve assembly 23 is maintained inoperative.

Although the details of the solenoid valve assembly 23 and carburetor 11 are not shown in FIGS. and 7, it will be understood that the solenoid valve assembly 23 in FIGS. 5 and 7 may be the same as the solenoid valve assembly 23 shown in FIG. 1 and that the carburetor 11 in FIGS. 5 and 7 may be the same as shown in FIG. 1A.

Although the control means to be used in the airpollution preventive system of this invention has been discussed as controlled on such variables as vehicle s eeds, and motion of the clutch pedal, the same can also be operated in accordance with the vacuum level in the intake manifold of the engine or revolution speed of the engine for detecting the high speed conditions of the motor vehicle.

It will now be appreciated from the foregoing description that the air-pollution preventive system according to the invention is advantageous in reducing the concentration of unburned toxis hydrocarbons in the engine exhaust gases during deceleration without affecting the engine performance. 1

What is claimed is:

1. In a vehicle having a gasoline internal combustion engine having an intake manifold and a carburetor provided with a mixing chamber within which gasoline vapor and air are mixed, a throttle downstream of said mixing chamber, means defining a deceleration passage communicating with said intake manifold downstream of said throttle and with said mixing chamber, said passageway being dimensioned to pass an air-fuel mixture of a volume and mixture ratio optimum for maintaining satisfactory combustion when the throttle is in a position corresponding to a deceleration from high speed operation of the vehicle, valve means in said passage, control means responsive to operation of the vehicle above a given speed setting corresponding to a mode for higher speed operation of the vehicle, above a given speed level and including means detecting said mode connected to said valve means for electrically controlling said valve means to open said deceleration passage during operation of said vehicle above said given speed setting and during deceleration without change in the driving condition of said vehicle corresponding to said given speed mode of operation, whereby said engine is supplied with said optimum air-fuel mixture in addition to the air-fuel mixture delivered to the engine delivered under control of said throttle, said valve means comprising a solenoid valve assembly having a valve normally closing said deceleration passage, a solenoid coil electrically connected to said control means for energization thereof under control of said control means, and a core connected to and movable with said valve head, said solenoid coil, when excited by said control means, forcing said core in a direction in which said valve head is retracted from said position closing said passage to a retracted position to open said deceleration passage, said control means comprising a switch means, comprising a moving member made of an insulating material and projecting toward a moving object, a moving contact mounted on said moving member at its end opposite to said moving object, an insulating member mounted on said moving contact, a compression spring positioned behind said insulating member to force said moving member toward said moving object, a pair of stationary contacts positioned to usually abut agains said moving contact and said insulating members by the action of said compression spring, and said moving contact being moved against the action of said spring to a position to abut against said stationary contacts when said moving object moves to depress said moving member. 

1. In a vehicle having a gasoline internal combustion engine having an intake manifold and a carburetor provided with a mixing chamber within which gasoline vapor and air are mixed, a throttle downstream of said mixing chamber, means defining a deceleration passage communicating with said intake manifold downstream of said throttle and with said mixing chamber, said passageway being dimensioned to pass an air-fuel mixture of a volume and mixture ratio optimum for maintaining satisfactory combustion when the throttle is in a position corresponding to a deceleration from high speed operation of the vehicle, valve means in said passage, control means responsive to operation of the vehicle above a given speed setting corresponding to a mode for higher speed operation of the vehicle, above a given speed level and including means detecting said mode connected to said valve means for electrically controlling said valve means to open said deceleration passage during operation of said vehicle above said given speed setting and during deceleration without change in the driving condition of said vehicle corresponding to said given speed mode of operation, whereby said engine is supplied with said optimum air-fuel mixture in addition to the air-fuel mixture delivered to the engine delivered under control of said throttle, said valve means comprising a solenoid valve assembly having a valve normally closing said deceleration passaGe, a solenoid coil electrically connected to said control means for energization thereof under control of said control means, and a core connected to and movable with said valve head, said solenoid coil, when excited by said control means, forcing said core in a direction in which said valve head is retracted from said position closing said passage to a retracted position to open said deceleration passage, said control means comprising a switch means, comprising a moving member made of an insulating material and projecting toward a moving object, a moving contact mounted on said moving member at its end opposite to said moving object, an insulating member mounted on said moving contact, a compression spring positioned behind said insulating member to force said moving member toward said moving object, a pair of stationary contacts positioned to usually abut agains said moving contact and said insulating members by the action of said compression spring, and said moving contact being moved against the action of said spring to a position to abut against said stationary contacts when said moving object moves to depress said moving member. 